A field study of the effects of a monovalent Leptospira borgpetersenii serovar Hardjo strain hardjobovis vaccine administered with oxytetracycline on reproductive performance in beef cattle

Abstract

Results suggested that under the conditions of the present study, administration of a monovalent Leptospira vaccine in conjunction with systemic administration of oxytetracycline did not significantly improve reproductive performance of beef cows.

Effect of a monovalent vaccine against Leptospira borgpetersenii serovar Hardjo strain hardjobovis on fertility in Holstein dairy cattle

“…The results are congruent with those obtained from another study 3 in which effects were evaluated of the same vaccine protocol on reproductive performance in naturally infected beef cattle. In that study 3 as in ours, the vaccine protocol did not significantly improve pregnancy and calving rates.…”

“…Similar to the protocol in the other study, 3 oxytetracycline was administered (20 mg/kg) to eliminate any existing or persistent Leptospira infections and to decrease transmission of leptospirosis among cattle in the herd. 17 Use of antimicrobials in conjunction with initial vaccination was intended to initiate a primary antibody response against the pathogen and allow cattle to remain uninfected until the time of second vaccination between 28 and 35 days after first vaccination.…”

“…A larger study 23 of naturally infected dairy cattle that received the same monovalent hardjobovis vaccine resulted in an increase in conception rates at first service; however, the specific strain of Leptospira was not identified and the reproductive efficiency variables evaluated were of limited scope, compared with those evaluated in similar studies. A third study 3 of beef cattle that received the monovalent vaccine coupled with long-acting oxytetracycline revealed no significant improvement in reproductive performance in naturally infected herds.…”

“…Spirochete replication in the reproductive tract increases the potential for venereal and transplacental transmission, 17 whereas persistent infection of the reproductive tract can lead to early embryonic death, abortion, stillbirth, and birth of weak calves. 3,17,18 Persistent infection of the reproductive tract in female cattle is the most economically important manifestation of serovar Hardjo. 1,17 Although the mechanisms are not fully understood, researchers presume that after bacteremia and bacteriuria, spirochetes can persist in the oviduct and uterus, interfering with embryo implantation and other early pregnancy events.…”

“…5,21 Research into the efficacy of a commercially available monovalent strain hardjobovis vaccine has been conducted; however, findings were inconclusive. 3,22,23 In a small study 22 of vaccinated beef heifers experimentally challenged with strain hardjobovis, renal and uterine tissue colonization with leptospires was prevented and urinary shedding of leptospires was eliminated. Although it is feasible that the heifers would also have a lower likelihood of reproductive tract colonization with the organism than would cows, reproductive performance was not assessed.…”